The Bioactivity Of The Extract From The Root Of Stellera Chamaejasme L. Against Pieris Rapae L. And The Preliminary Studies On The Mechanism

The bioactivity and the mechanism of the three extracts from the root of Stellera chamaejasme against the Pieris rapae were tested based on the studies on the 25 kinds of poisonous plant species against the larvae of Pieris rapae. Three extracts were the ethanol extract (SCEE) from the root of Stellera chamaejasme, the n-hexane extract (SCNE) from SCEE, the chromatographic extract (SCCE) from SCNE. Three extracts were all tested for the toxicity and the antifeedant activity. The contact toxicity and stomach toxicity of SCCE against the larvae were tested. SCNE was tested for the influence of growth and development of the larvae, the effect of fecundity, the oviposition deterrent activity and ovicidal activity of the adults. The inhibitory activity of acetylcholinesterase activity and carboxylesterase activity of SCNE and SCCE were tested. Through observing that the poisoning symptom, the dead larvae's external morphogenesis, we studied on the mechanism of the toxicity.The results showed that the extracts from the Stellera chamaejasme had significant good toxicity and stronger antifeedant activity, and the ordinal scale of the toxicity and the antifeedant activity of the extracts both were SCCE > SCNE > SCEE, and the no-choice anti-feeding was better than the choice anti-feeding of the experimentation of antifeedant activity treated with SCCE. And the results of the experimentation of the action of the toxicity treated with SCCE showed well contact toxicity and some stomach toxicity. Through the observation of the poisoning symptom, we preliminarily conjectured the insect's nervous system as one of the extracts' targets. The experimentation on the growth and development showed that the SCNE had significant good inhibitory effects, with the most malformation of the prepupa, the pupae and the mature. There were little inhibitory effects of fecunditysome the oviposition deterrent activity and a little ovicidal activity. And the results showed that the extracts had better inhibitory activity of acetylcholinesterase and some good inhibitory activity of carboxylesterase. In a word, the target of the extract from the root of Stellera chamaejasme against the larvae of Pieris rapae was the insect's nervous system based on results of the studies on the bioactivity, observation of the poisoning symptom and the mechanism mentioned above.